In setting up a scaffold frame upwardly from below at construction sites, the scaffold frame members have to be linked to each other, one above the other. Linking members are conventionally employed for this purpose, including a linkage pin projected through each of the right and left upper ends of the lower scaffold frame member, and each of the right and left lower ends of the upper scaffold frame member. An arcuate locking arm is applied on each side to join the upper and lower members. Or, as disclosed in Japanese published utility model No. Hei. 1-131753, a linkage pin is inserted between upper and lower scaffold frame members, and by rotating the linkage pins by a specified angle, the concave and convex parts of the scaffold frame and linkage pin are mutually engaged with each other, thereby linking the upper and lower scaffold frame members.
In such prior art structures, apart from the procedure of inserting the upper scaffold frame member into the lower scaffold frame member the locking arms at the right and left sides have to be locked in place while keeping together the upper and lower scaffold frame members, or the right and left linkage pins, have to be rotated between the two frame members, and at least two workers are required to create the linkage, and the linking procedure is complicated and inefficient.